Memory access bounds checking for a programmable atomic operator

ABSTRACT

Devices and techniques for memory access bounds checking for a programmable atomic operator are described herein. A processor can execute a programmable atomic operator with a base memory address. The processor can obtain a memory interleave size indicator corresponding to the programmable atomic operator and calculate a contiguous memory address range from the base memory address and the memory interleave size. The processor can then detect that a memory request from the programmable atomic operator is outside the contiguous memory address range and deny the memory request when it is outside of the contiguous memory address range and allow the memory request otherwise.

STATEMENT REGARDING GOVERNMENT SUPPORT

This invention was made with U.S. Government support under Agreement No.HR00111890003, awarded by DARPA. The U.S. Government has certain rightsin the invention.

BACKGROUND

Chiplets are an emerging technique for integrating various processingfunctionalities. Generally, a chiplet system is made up of discretemodules (each a “chiplet”) that are integrated on an interposer, and inmany examples interconnected as desired through one or more establishednetworks, to provide a system with the desired functionality. Theinterposer and included chiplets can be packaged together to facilitateinterconnection with other components of a larger system. Each chipletcan include one or more individual integrated circuits (ICs), or“chips”, potentially in combination with discrete circuit components,and commonly coupled to a respective substrate to facilitate attachmentto the interposer. Most or all chiplets in a system will be individuallyconfigured for communication through the one or more establishednetworks.

The configuration of chiplets as individual modules of a system isdistinct from such a system being implemented on single chips thatcontain distinct device blocks (e.g., intellectual property (IP) blocks)on one substrate (e.g., single die), such as a system-on-a-chip (SoC),or multiple discrete packaged devices integrated on a printed circuitboard (PCB). In general, chiplets provide better performance (e.g.,lower power consumption, reduced latency, etc.) than discrete packageddevices, and chiplets provide greater production benefits than singledie chips. These production benefits can include higher yields orreduced development costs and time.

Chiplet systems can include, for example, one or more application (orprocessor) chiplets and one or more support chiplets. Here, thedistinction between application and support chiplets is simply areference to the likely design scenarios for the chiplet system. Thus,for example, a synthetic vision chiplet system can include, by way ofexample only, an application chiplet to produce the synthetic visionoutput along with support chiplets, such as a memory controller chiplet,a sensor interface chiplet, or a communication chiplet. In a typical usecase, the synthetic vision designer can design the application chipletand source the support chiplets from other parties. Thus, the designexpenditure (e.g., in terms of time or complexity) is reduced because byavoiding the design and production of functionality embodied in thesupport chiplets. Chiplets also support the tight integration of IPblocks that can otherwise be difficult, such as those manufactured usingdifferent processing technologies or using different feature sizes (orutilizing different contact technologies or spacings). Thus, multipleIC's or IC assemblies, with different physical, electrical, orcommunication characteristics can be assembled in a modular manner toprovide an assembly providing desired functionalities. Chiplet systemscan also facilitate adaptation to suit needs of different larger systemsinto which the chiplet system will be incorporated. In an example, IC'sor other assemblies can be optimized for the power, speed, or heatgeneration for a specific function—as can happen with sensors—can beintegrated with other devices more easily than attempting to do so on asingle die. Additionally, by reducing the overall size of the die, theyield for chiplets tends to be higher than that of more complex, singledie devices.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be understood more fully from the detaileddescription given below and from the accompanying drawings of variousembodiments of the disclosure. The drawings, however, should not betaken to limit the disclosure to the specific embodiments, but are forexplanation and understanding only.

FIGS. 1A and 1B illustrate an example of a chiplet system, according toan embodiment.

FIG. 2 illustrates components of an example of a memory controllerchiplet, according to an embodiment.

FIG. 3 illustrates components of an example of a memory controllerchiplet, according to an embodiment.

FIG. 4 illustrates components in an example of a programmable atomicunit (PAU), according to an embodiment.

FIG. 5 illustrates a chiplet protocol interface request packet,according to an embodiment.

FIG. 6 illustrates a chiplet protocol interface response packet,according to an embodiment.

FIG. 7 is a flow chart of an example of a method for memory accessbounds checking for a programmable atomic operator, according to anembodiment.

FIG. 8 is a block diagram of an example of a machine with which, inwhich, or by which embodiments of the present disclosure can operate.

DETAILED DESCRIPTION

FIG. 1, described below, offers an example of a chiplet system and thecomponents operating therein. The illustrated chiplet system includes amemory controller. The chiplet system includes a packet-based network tocommunicate between chiplets. The memory controller includes aprogrammable atomic unit (PAU) with a processor to execute a customprogram, a programmable atomic operator (PAO), in response to a memoryrequest for the programmable atomic operator. Additional details aboutthe PAU are described below with respect to FIGS. 2 and 4.

Generally, PAU implementations will be small and efficient because theyare included in a memory controller and are intended to performgenerally small operations on portions of the memory. Accordingly, PAUsdo not tend to have all of the components attributed to moderncomputing. For example, PAUs will tend to operate on physical memoryaddresses and omit virtual memory features supported by a memorymanagement unit (MMU) as is common in traditional computerarchitectures.

An issue can arise in PAUs by omitting memory management features suchas those provided by an MMU. Specifically, bounds checking memoryaddress requests by PAOs executing on the PAU. Such bounds checking canoffer several benefits by preventing one program from inadvertently orintentionally corrupting the working memory of another executingprogram. Thus, process memory (e.g., implemented in virtual memory) andthe hardware to support memory access constraints can prevent poorlyfunctioning or malicious programs from effecting other processes of asystem. The absence of these facilities in a PAU can lead to datacorruption or compromise secure operation of the PAU.

To address the issue of bounds checking memory requests by executingPAOs in a PAU, a contiguous region of memory, that is managed by thememory controller of the PAU, that the PAO is allowed to access iscalculated from a base memory address used to invoke the PAO. Thus, aPAO executed within the PAU can only access the memory managed by thatmemory controller and is both virtually contiguous in the applicationand physically contiguous within a memory controller. This restrictionensures that a PAO only accesses memory owned by an issuing process(e.g., program or application).

Generally, memory for a process is interleaved across memory controllersto minimize hot spots. A flexible interleave size can be used to enablePAOs to access large data structures. Interleave sizes of 256-byte,16-kilobyte, 1-megabyte, or 64-megabyte can be used, for example, with adefault memory interleave size of 256-bytes. Thus, the contiguousvirtual address space of the process would, using the default interleavesize, have 256-bytes with a first memory controller, then the next256-bytes would be with a second memory controller, and so on.

A PAO request to the memory controller can provide both a base memoryaddress and a value between zero and three that represents theinterleave size. These two pieces of information can be used to specifythe valid address access range for the PAO. For example, the beginningof the access range can be aligned to the interleave size. Accessoutside the valid address range by the PAO can cause a failure status tobe returned to the issuer. Thus, PAO memory access is limited to thelargest region of memory that is contiguous in the requesting program'svirtual address space that contains the PAO request address. Becausethis block of memory is no bigger than the interleave size, and iscontiguous, then the PAO is restricted to access memory that is withinthe process space (e.g., virtual memory) of the requesting process.Thus, the benefits of an MMU can be achieved without the complexity inthe PAU. Additional details and examples are provided below.

FIGS. 1A and 1B illustrate an example of a chiplet system 110, accordingto an embodiment. FIG. 1A is a representation of the chiplet system 110mounted on a peripheral board 105, that can be connected to a broadercomputer system by a peripheral component interconnect express (PCIe),for example. The chiplet system 110 includes a package substrate 115, aninterposer 120, and four chiplets, an application chiplet 125, a hostinterface chiplet 135, a memory controller chiplet 140, and a memorydevice chiplet 150. Other systems can include many additional chipletsto provide additional functionalities as will be apparent from thefollowing discussion. The package of the chiplet system 110 isillustrated with a lid or cover 165, though other packaging techniquesand structures for the chiplet system can be used. FIG. 1B is a blockdiagram labeling the components in the chiplet system for clarity.

The application chiplet 125 is illustrated as including anetwork-on-chip (NOC) 130 to support a chiplet network 155 forinter-chiplet communications. In example embodiments NOC 130 can beincluded on the application chiplet 125. In an example, NOC 130 can bedefined in response to selected support chiplets (e.g., chiplets 135,140, and 150) thus enabling a designer to select an appropriate numberor chiplet network connections or switches for the NOC 130. In anexample, the NOC 130 can be located on a separate chiplet, or evenwithin the interposer 120. In examples as discussed herein, the NOC 130implements a chiplet protocol interface (CPI) network.

The CPI is a packet-based network that supports virtual channels toenable a flexible and high-speed interaction between chiplets. CPIenables bridging from intra-chiplet networks to the chiplet network 155.For example, the Advanced eXtensible Interface (AXI) is a widely usedspecification to design intra-chip communications. AXI specifications,however, cover a great variety of physical design options, such as thenumber of physical channels, signal timing, power, etc. Within a singlechip, these options are generally selected to meet design goals, such aspower consumption, speed, etc. However, to achieve the flexibility ofthe chiplet system, an adapter, such as CPI, is used to interfacebetween the various AXI design options that can be implemented in thevarious chiplets. By enabling a physical channel to virtual channelmapping and encapsulating time-based signaling with a packetizedprotocol, CPI bridges intra-chiplet networks across the chiplet network155.

CPI can use a variety of different physical layers to transmit packets.The physical layer can include simple conductive connections, or caninclude drivers to increase the voltage, or otherwise facilitatetransmitting the signals over longer distances. An example of one suchphysical layer can include the Advanced Interface Bus (AIB), which invarious examples, can be implemented in the interposer 120. AIBtransmits and receives data using source synchronous data transfers witha forwarded clock. Packets are transferred across the AIB at single datarate (SDR) or dual data rate (DDR) with respect to the transmittedclock. Various channel widths are supported by AIB. AIB channel widthsare in multiples of 20 bits when operated in SDR mode (20, 40, 60, . . .), and multiples of 40 bits for DDR mode: (40, 80, 120, . . . ). The AIBchannel width includes both transmit and receive signals. The channelcan be configured to have a symmetrical number of transmit (TX) andreceive (RX) input/outputs (I/Os), or have a non-symmetrical number oftransmitters and receivers (e.g., either all transmitters or allreceivers). The channel can act as an AIB principal or subordinatedepending on which chiplet provides the principal clock. AIB I/O cellssupport three clocking modes: asynchronous (i.e. non-clocked), SDR, andDDR. In various examples, the non-clocked mode is used for clocks andsome control signals. The SDR mode can use dedicated SDR only I/O cells,or dual use SDR/DDR I/O cells.

In an example, CPI packet protocols (e.g., point-to-point or routable)can use symmetrical receive and transmit I/O cells within an AIBchannel. The CPI streaming protocol allows more flexible use of the AIBI/O cells. In an example, an AIB channel for streaming mode canconfigure the I/O cells as all TX, all RX, or half TX and half RX. CPIpacket protocols can use an AIB channel in either SDR or DDR operationmodes. In an example, the AIB channel is configured in increments of 80I/O cells (i.e. 40 TX and 40 RX) for SDR mode and 40 I/O cells for DDRmode. The CPI streaming protocol can use an AIB channel in either SDR orDDR operation modes. Here, in an example, the AIB channel is inincrements of 40 I/O cells for both SDR and DDR modes. In an example,each AIB channel is assigned a unique interface identifier. Theidentifier is used during CPI reset and initialization to determinepaired AIB channels across adjacent chiplets. In an example, theinterface identifier is a 20-bit value comprising a seven-bit chipletidentifier, a seven-bit column identifier, and a six-bit linkidentifier. The AIB physical layer transmits the interface identifierusing an AIB out-of-band shift register. The 20-bit interface identifieris transferred in both directions across an AIB interface using bits32-51 of the shift registers.

AIB defines a stacked set of AIB channels as an AIB channel column. AnAIB channel column has some number of AIB channels, plus an auxiliarychannel. The auxiliary channel contains signals used for AIBinitialization. All AIB channels (other than the auxiliary channel)within a column are of the same configuration (e.g., all TX, all RX, orhalf TX and half RX, as well as having the same number of data I/Osignals). In an example, AIB channels are numbered in continuousincreasing order starting with the AIB channel adjacent to the AUXchannel. The AIB channel adjacent to the AUX is defined to be AIBchannel zero.

Generally, CPI interfaces on individual chiplets can includeserialization-deserialization (SERDES) hardware. SERDES interconnectswork well for scenarios in which high-speed signaling with low signalcount are desirable. SERDES, however, can result in additional powerconsumption and longer latencies for multiplexing and demultiplexing,error detection or correction (e.g., using block level cyclic redundancychecking (CRC)), link-level retry, or forward error correction. However,when low latency or energy consumption is a primary concern forultra-short reach, chiplet-to-chiplet interconnects, a parallelinterface with clock rates that allow data transfer with minimal latencycan be utilized. CPI includes elements to minimize both latency andenergy consumption in these ultra-short reach chiplet interconnects.

For flow control, CPI employs a credit-based technique. A recipient,such as the application chiplet 125, provides a sender, such as thememory controller chiplet 140, with credits that represent availablebuffers. In an example, a CPI recipient includes a buffer for eachvirtual channel for a given time-unit of transmission. Thus, if the CPIrecipient supports five messages in time and a single virtual channel,the recipient has five buffers arranged in five rows (e.g., one row foreach unit time). If four virtual channels are supported, then therecipient has twenty buffers arranged in five rows. Each buffer holdsthe payload of one CPI packet.

When the sender transmits to the recipient, the sender decrements theavailable credits based on the transmission. Once all credits for therecipient are consumed, the sender stops sending packets to therecipient. This ensures that the recipient always has an availablebuffer to store the transmission.

As the recipient processes received packets and frees buffers, therecipient communicates the available buffer space back to the sender.This credit return can then be used by the sender allow transmitting ofadditional information.

Also illustrated is a chiplet mesh network 160 that uses a direct,chiplet-to-chiplet technique without the need for the NOC 130. Thechiplet mesh network 160 can be implemented in CPI, or anotherchiplet-to-chiplet protocol. The chiplet mesh network 160 generallyenables a pipeline of chiplets where one chiplet serves as the interfaceto the pipeline while other chiplets in the pipeline interface only withthemselves.

Additionally, dedicated device interfaces, such as one or more industrystandard memory interfaces 145 (such as, for example, synchronous memoryinterfaces, such as DDR5, DDR 6), can also be used to interconnectchiplets. Connection of a chiplet system or individual chiplets toexternal devices (such as a larger system can be through a desiredinterface (for example, a PCIE interface). Such as external interfacecan be implemented, in an example, through a host interface chiplet 135,which in the depicted example, provides a PCIE interface external tochiplet system 110. Such dedicated interfaces 145 are generally employedwhen a convention or standard in the industry has converged on such aninterface. The illustrated example of a Double Data Rate (DDR) interface145 connecting the memory controller chiplet 140 to a dynamic randomaccess memory (DRAM) memory device 150 is just such an industryconvention.

Of the variety of possible support chiplets, the memory controllerchiplet 140 is likely present in the chiplet system 110 due to the nearomnipresent use of storage for computer processing as well assophisticated state-of-the-art for memory devices. Thus, using memorydevice chiplets 150 and memory controller chiplets 140 produced byothers gives chiplet system designers access to robust products bysophisticated producers. Generally, the memory controller chiplet 140provides a memory device specific interface to read, write, or erasedata. Often, the memory controller chiplet 140 can provide additionalfeatures, such as error detection, error correction, maintenanceoperations, or atomic operator execution. For some types of memory,maintenance operations tend to be specific to the memory device 150,such as garbage collection in NAND flash or storage class memories,temperature adjustments (e.g., cross temperature management) in NANDflash memories. In an example, the maintenance operations can includelogical-to-physical (L2P) mapping or management to provide a level ofindirection between the physical and logical representation of data. Inother types of memory, for example DRAM, some memory operations, such asrefresh can be controlled by a host processor or of a memory controllerat some times, and at other times controlled by the DRAM memory device,or by logic associated with one or more DRAM devices, such as aninterface chip (in an example, a buffer).

Atomic operators are a data manipulation that, for example, can beperformed by the memory controller chiplet 140. In other chipletsystems, the atomic operators can be performed by other chiplets. Forexample, an atomic operator of “increment” can be specified in a commandby the application chiplet 125, the command including a memory addressand possibly an increment value. Upon receiving the command, the memorycontroller chiplet 140 retrieves a number from the specified memoryaddress, increments the number by the amount specified in the command,and stores the result. Upon a successful completion, the memorycontroller chiplet 140 provides an indication of the commands success tothe application chiplet 125. Atomic operators avoid transmitting thedata across the chiplet network 160, resulting in lower latencyexecution of such commands.

Atomic operators can be classified as built-in atomics or programmable(e.g., custom) atomics. Built-in atomics are a finite set of operationsthat are immutably implemented in hardware. Programmable atomics aresmall programs that can execute on a programmable atomic unit (PAU)(e.g., a custom atomic unit (CAU)) of the memory controller chiplet 140.FIG. 1 illustrates an example of a memory controller chiplet thatdiscusses a PAU.

The memory device chiplet 150 can be, or include any combination of,volatile memory devices or non-volatile memories. Examples of volatilememory devices include, but are not limited to, random access memory(RAM)—such as DRAM) synchronous DRAM (SDRAM), graphics double data ratetype 6 SDRAM (GDDR6 SDRAM), among others. Examples of non-volatilememory devices include, but are not limited to, negative-and-(NAND)-typeflash memory, storage class memory (e.g., phase-change memory ormemristor based technologies), ferroelectric RAM (FeRAM), among others.The illustrated example includes the memory device 150 as a chiplet,however, the memory device 150 can reside elsewhere, such as in adifferent package on the peripheral board 105. For many applications,multiple memory device chiplets can be provided. In an example, thesememory device chiplets can each implement one or multiple storagetechnologies. In an example, a memory chiplet can include, multiplestacked memory die of different technologies, for example one or morestatic random access memory (SRAM) devices stacked or otherwise incommunication with one or more dynamic random access memory (DRAM)devices. Memory controller 140 can also serve to coordinate operationsbetween multiple memory chiplets in chiplet system 110; for example, toutilize one or more memory chiplets in one or more levels of cachestorage, and to use one or more additional memory chiplets as mainmemory. Chiplet system 110 can also include multiple memory controllers140, as can be used to provide memory control functionality for separateprocessors, sensors, networks, etc. A chiplet architecture, such aschiplet system 110 offers advantages in allowing adaptation to differentmemory storage technologies; and different memory interfaces, throughupdated chiplet configurations, without requiring redesign of theremainder of the system structure.

FIG. 2 illustrates components of an example of a memory controllerchiplet 205, according to an embodiment. The memory controller chiplet205 includes a cache 210, a cache controller 215, an off-die memorycontroller 220 (e.g., to communicate with off-die memory 275), a networkcommunication interface 225 (e.g., to interface with a chiplet network285 and communicate with other chiplets), and a set of atomic and mergeunits 250. Members of this set can include, for example, a write mergeunit 255, a memory hazard unit 260, built-in atomic unit 265, or a PAU270. The various components are illustrated logically, and not as theynecessarily would be implemented. For example, the built-in atomic unit265 likely comprises different devices along a path to the off-diememory. For example, the built-in atomic unit 265 could be in aninterface device/buffer on a memory chiplet, as discussed above. Incontrast, the programmable atomic unit 270 could be implemented in aseparate processor on the memory controller chiplet 205 (but in variousexamples can be implemented in other locations, for example on a memorychiplet).

The off-die memory controller 220 is directly coupled to the off-diememory 275 (e.g., via a bus or other communication connection) toprovide write operations and read operations to and from the one or moreoff-die memory, such as off-die memory 275 and off-die memory 280. Inthe depicted example, the off-die memory controller 220 is also coupledfor output to the atomic and merge unit 250, and for input to the cachecontroller 215 (e.g., a memory side cache controller).

In the example configuration, cache controller 215 is directly coupledto the cache 210, and can be coupled to the network communicationinterface 225 for input (such as incoming read or write requests), andcoupled for output to the off-die memory controller 220.

The network communication interface 225 includes a packet decoder 230,network input queues 235, a packet encoder 240, and network outputqueues 245 to support a packet-based chiplet network 285, such as CPI.The chiplet network 285 can provide packet routing between and amongprocessors, memory controllers, hybrid threading processors,configurable processing circuits, or communication interfaces. In such apacket-based communication system, each packet typically includesdestination and source addressing, along with any data payload orinstruction. In an example, the chiplet network 285 can be implementedas a collection of crossbar switches having a folded Clos configuration,or a mesh network providing for additional connections, depending uponthe configuration.

In various examples, the chiplet network 285 can be part of anasynchronous switching fabric. Here, a data packet can be routed alongany of various paths, such that the arrival of any selected data packetat an addressed destination can occur at any of multiple differenttimes, depending upon the routing. Additionally, chiplet network 285 canbe implemented at least in part as a synchronous communication network,such as a synchronous mesh communication network. Both configurations ofcommunication networks are contemplated for use for examples inaccordance with the present disclosure.

The memory controller chiplet 205 can receive a packet having, forexample, a source address, a read request, and a physical address. Inresponse, the off-die memory controller 220 or the cache controller 215will read the data from the specified physical address (which can be inthe off-die memory 275 or in the cache 210), and assemble a responsepacket to the source address containing the requested data. Similarly,the memory controller chiplet 205 can receive a packet having a sourceaddress, a write request, and a physical address. In response, thememory controller chiplet 205 will write the data to the specifiedphysical address (which can be in the cache 210 or in the off-diememories 275 or 280), and assemble a response packet to the sourceaddress containing an acknowledgement that the data was stored to amemory.

Thus, the memory controller chiplet 205 can receive read and writerequests via the chiplet network 285 and process the requests using thecache controller 215 interfacing with the cache 210, if possible. If therequest cannot be handled by the cache controller 215, the off-diememory controller 220 handles the request by communication with theoff-die memories 275 or 280, the atomic and merge unit 250, or both. Asnoted above, one or more levels of cache can also be implemented inoff-die memories 275 or 280; and in some such examples can be accesseddirectly by cache controller 215. Data read by the off-die memorycontroller 220 can be cached in the cache 210 by the cache controller215 for later use.

The atomic and merge unit 250 are coupled to receive (as input) theoutput of the off-die memory controller 220, and to provide output tothe cache 210, the network communication interface 225, or directly tothe chiplet network 285. The memory hazard unit 260, write merge unit255 and the built-in (e.g., predetermined) atomic unit 265 can each beimplemented as state machines with other combinational logic circuitry(such as adders, shifters, comparators, AND gates, OR gates, XOR gates,or any suitable combination thereof) or other logic circuitry. Thesecomponents can also include one or more registers or buffers to storeoperand or other data. The PAU 270 can be implemented as one or moreprocessor cores or control circuitry, and various state machines withother combinational logic circuitry or other logic circuitry, and canalso include one or more registers, buffers, or memories to storeaddresses, executable instructions, operand and other data, or can beimplemented as a processor.

The write merge unit 255 receives read data and request data, and mergesthe request data and read data to create a single unit having the readdata and the source address to be used in the response or return datapacket). The write merge unit 255 provides the merged data to the writeport of the cache 210 (or, equivalently, to the cache controller 215 towrite to the cache 210). Optionally, the write merge unit 255 providesthe merged data to the network communication interface 225 to encode andprepare a response or return data packet for transmission on the chipletnetwork 285.

When the request data is for a built-in atomic operator, the built-inatomic unit 265 receives the request and reads data, either from thewrite merge unit 255 or directly from the off-die memory controller 220.The atomic operator is performed, and using the write merge unit 255,the resulting data is written to the cache 210, or provided to thenetwork communication interface 225 to encode and prepare a response orreturn data packet for transmission on the chiplet network 285.

The built-in atomic unit 265 handles predefined atomic operators such asfetch-and-increment or compare-and-swap. In an example, these operationsperform a simple read-modify-write operation to a single memory locationof 32-bytes or less in size. Atomic memory operations are initiated froma request packet transmitted over the chiplet network 285. The requestpacket has a physical address, atomic operator type, operand size, andoptionally up to 32-bytes of data. The atomic operator performs theread-modify-write to a cache memory line of the cache 210, filling thecache memory if necessary. The atomic operator response can be a simplecompletion response, or a response with up to 32-bytes of data. Exampleatomic memory operators include fetch-and-AND, fetch-and-OR,fetch-and-XOR, fetch-and-add, fetch-and-subtract, fetch-and-increment,fetch-and-decrement, fetch-and-minimum, fetch-and-maximum,fetch-and-swap, and compare-and-swap. In various example embodiments,32-bit and 64-bit operations are supported, along with operations on 16or 32 bytes of data. Methods disclosed herein are also compatible withhardware supporting larger or smaller operations and more or less data.

Built-in atomic operators can also involve requests for a “standard”atomic operator on the requested data, such as comparatively simple,single cycle, integer atomics—such as fetch-and-increment orcompare-and-swap—which will occur with the same throughput as a regularmemory read or write operation not involving an atomic operator. Forthese operations, the cache controller 215 can generally reserve a cacheline in the cache 210 by setting a hazard bit (in hardware), so that thecache line cannot be read by another process while it is in transition.The data is obtained from either the off-die memory 275 or the cache210, and is provided to the built-in atomic unit 265 to perform therequested atomic operator. Following the atomic operator, in addition toproviding the resulting data to the packet encoder 240 to encodeoutgoing data packets for transmission on the chiplet network 285, thebuilt-in atomic unit 265 provides the resulting data to the write mergeunit 255, which will also write the resulting data to the cache 210.Following the writing of the resulting data to the cache 210, anycorresponding hazard bit which was set will be cleared by the memoryhazard unit 260.

The PAU 270 enables high performance (high throughput and low latency)for programmable atomic operators (also referred to as “custom atomictransactions” or “custom atomic operators”), comparable to theperformance of built-in atomic operators. Rather than executing multiplememory accesses, in response to an atomic operator request designating aprogrammable atomic operator and a memory address, circuitry in thememory controller chiplet 205 transfers the atomic operator request toPAU 270 and sets a hazard bit stored in a memory hazard registercorresponding to the memory address of the memory line used in theatomic operator, to ensure that no other operation (read, write, oratomic) is performed on that memory line, which hazard bit is thencleared upon completion of the atomic operator. Additional, direct datapaths provided for the PAU 270 executing the programmable atomicoperators allow for additional write operations without any limitationsimposed by the bandwidth of the communication networks and withoutincreasing any congestion of the communication networks.

The PAU 270 includes a multi-threaded processor, for example, such as aRISC-V ISA based multi-threaded processor, having one or more processorcores, and further having an extended instruction set for executingprogrammable atomic operators. When provided with the extendedinstruction set for executing programmable atomic operators, the PAU 270can be embodied as one or more hybrid threading processors. In someexample embodiments, the PAU 270 provides barrel-style, round-robininstantaneous thread switching to maintain a high instruction-per-clockrate.

Programmable atomic operators can be performed by the PAU 270 involvingrequests for a programmable atomic operator on the requested data. Auser can prepare programming code to provide such programmable atomicoperators. For example, the programmable atomic operators can becomparatively simple, multi-cycle operations such as floating-pointaddition, or comparatively complex, multi-instruction operations such asa Bloom filter insert. The programmable atomic operators can be the sameas or different than the predetermined atomic operators, insofar as theyare defined by the user rather than a system vendor. For theseoperations, the cache controller 215 can reserve a cache line in thecache 210, by setting a hazard bit (in hardware), so that cache linecannot be read by another process while it is in transition. The data isobtained from either the cache 210 or the off-die memories 275 or 280,and is provided to the PAU 270 to perform the requested programmableatomic operator. Following the atomic operator, the PAU 270 will providethe resulting data to the network communication interface 225 todirectly encode outgoing data packets having the resulting data fortransmission on the chiplet network 285. In addition, the PAU 270 willprovide the resulting data to the cache controller 215, which will alsowrite the resulting data to the cache 210. Following the writing of theresulting data to the cache 210, any corresponding hazard bit which wasset will be cleared by the cache control circuit 215.

In selected examples, the approach taken for programmable atomicoperators is to provide multiple, generic, custom atomic request typesthat can be sent through the chiplet network 285 to the memorycontroller chiplet 205 from an originating source such as a processor orother system component. The cache controllers 215 or off-die memorycontroller 220 identify the request as a custom atomic and forward therequest to the PAU 270. In a representative embodiment, the PAU 270: (1)is a programmable processing element capable of efficiently performing auser defined atomic operator; (2) can perform load and stores to memory,arithmetic and logical operations and control flow decisions; and (3)leverages the RISC-V ISA with a set of new, specialized instructions tofacilitate interacting with such controllers 215, 220 to atomicallyperform the user-defined operation. In desirable examples, the RISC-VISA contains a full set of instructions that support high level languageoperators and data types. The PAU 270 can leverage the RISC-V ISA, butwill commonly support a more limited set of instructions and limitedregister file size to reduce the die size of the unit when includedwithin the memory controller chiplet 205.

As mentioned above, prior to the writing of the read data to the cache210, the set hazard bit for the reserved cache line is to be cleared, bythe memory hazard clear unit 260. Accordingly, when the request and readdata is received by the write merge unit 255, a reset or clear signalcan be transmitted by the memory hazard clear unit 260 to the cache 210to reset the set memory hazard bit for the reserved cache line. Also,resetting this hazard bit will also release a pending read or writerequest involving the designated (or reserved) cache line, providing thepending read or write request to an inbound request multiplexer forselection and processing.

FIG. 3 illustrates components of an example of a memory controllerchiplet, according to an embodiment. FIG. 3 is another representation ofa memory controller from the memory controller 205 illustrated in FIG.2. Many of the same components shown in FIG. 2 are illustrated here. Forexample, the cache 302 and 385 are examples of cache 210; DRAM(s) 340are examples of off-die memory 275-280; atomic/write merge 370 and theprogrammable atomic unit 380 may be an example of atomics and merge unit250. Other components of FIG. 3 may be examples of other components ofFIG. 2 such as off-die memory controller 220 and cache controller 215.

Other components, not specifically represented in the memory controller205, can include the following. A NOC Request Queue 305 to receiverequests from the network-on-chip and provide a small amount of queuing.An Atomic Request Queue 310 that receives requests from the programmableatomic unit 380 and provides a small amount of queuing. An InboundRequest Multiplexer (IRM) that selects between inbound memory requestsources. In an example, the three memory request sources, in order ofpriority are: Memory Hazard Requests, Atomic Requests, and Inbound NOCRequests.

The Cache (Read) 325 and Cache (Write) 375 are a single deviceimplemented as, in an example, an SRAM data cache. The diagramillustrates the cache as two separate blocks (325 and 375), oneproviding read access, the other providing write access. A Delay Block320 provides one or more pipeline stages to mimic the delay for an SRAMcache read operation. Generally, a cache miss accesses to the off-diememory 340 (e.g., off-die memory 280) to bring the desired data into thecache. While waiting for the memory response (e.g., access time for theDRAM 340), the memory line is not available for other requests. A MemoryHazard block (Set block 315 and Clear block 360) can maintain a table ofhazard bits indicating which memory lines are unavailable for access.Thus, an inbound request that tries to access a line with a hazard isheld by the Memory Hazard block until the hazard is cleared. Once thehazard is cleared then the request is resent through the Inbound RequestMultiplexer. In an example, the memory line tag address is hashed to ahazard bit index. The number of hazard bits may be chosen to set thehazard collision probability to a sufficiently low level.

An Inbound DRAM Control Multiplexer (IDCM) selects from an inbound NOCrequest and a cache eviction request. For the Bank Request Queues 330,each separately managed DRAM bank has a dedicated bank request queue tohold requests until they can be scheduled on the associated DRAM bank.

The scheduler 335 selects across the bank request queues 335 to choose arequest for an available DRAM bank. A Request Hit Data Queue 360 holdsrequest data from cache hits until selected. A Request Miss Data Queue355 holds data read from the DRAM(s) until selected. A Miss RequestQueue 350 is used to hold request packet information for cache missesuntil the request is selected. A Hit Request Queue 345 holds requestpacket information for cache hits until selected. A Data SelectionMultiplexer (DSM) selects between DRAM read data and cache hit readdata. The selected data is written to the SRAM cache. Request SelectionMultiplexer (RSM) selects between hit and miss request queues 345 and355.

The Atomic/Write Merge 370 either merges the request data and DRAM readdata, or, if the request is a built-in atomic (e.g., built-in atomicoperation block 265), the memory data and request data are used asinputs for an atomic operation. The Cache (Write) block 375 representsthe write port for the SRAM cache. Data from a NOC write request anddata from DRAM read operations are written to the SRAM cache. The MemoryHazard (Clear) block 365 represents the hazard clear operation for thememory hazard structure. Clearing a hazard may release a pending NOCrequest and send it to the Inbound Request Multiplexer. The programmableAtomic Unit 380 processes programmable atomic operations (e.g.,transactions). The NOC Outbound Response Multiplexer (ORM) selectsbetween memory controller responses and custom atomic unit responses andsends the selection to the NOC.

FIG. 4 illustrates components in an example of a programmable atomicunit 400 (PAU), such as those noted above with respect to FIG. 1 (e.g.,in the memory controller 140) and FIG. 2 (e.g., PAU 270), according toan embodiment. As illustrated, the PAU 400 includes a processor 405,local memory 410 (e.g., SRAM), and a controller 415 for the local memory410.

In an example, the processor 405 is a pipelined such that multiplestages of different instructions are executed together per clock cycle.The processor 405 is also a barrel-multithreaded processor, withcircuitry to switch between different register files (e.g., sets ofregisters containing current processing state) upon each clock cycle ofthe processor 405. This enables efficient context switching betweencurrently executing threads. In an example, the processor 405 supportseight threads, resulting in eight register files. In an example, some orall of the register files are not integrated into the processor 405, butrather reside in the local memory 410 (registers 420). This reducescircuit complexity in the processor 405 by eliminating the traditionalflip-flops used for these registers 420.

The local memory 410 can also house a cache 430 and instructions 425 foratomic operators. The atomic instructions 425 comprise sets ofinstructions to support the various application-loaded atomic operators.When an atomic operator is requested—by the application chiplet 125, forexample—a set of instructions (e.g., a kernel) corresponding to theatomic operator are executed by the processor 405. In an example, theatomic instructions 425 are partitioned to establish the sets ofinstructions. In this example, the specific programmable atomic operatorbeing requested by a requesting process can identify the programmableatomic operator by the partition number. The partition number can beestablished when the programmable atomic operator is registered with(e.g., loaded onto) the PAU 400. Additional metadata for theprogrammable atomic instructions 425 can also be stored in the localmemory 410, such as the partition tables.

Atomic operators manipulate the cache 430, which is generallysynchronized (e.g., flushed) when a thread for an atomic operatorcompletes. Thus, aside from initial loading from the external memory,such as the off-die memory 275 or 280, latency is reduced for mostmemory operations during execution of a programmable atomic operatorthread.

A variety of components could implement memory access bounds checkingfor an atomic operator, such as the processor 405, unillustratedcircuitry on the illustrated path to the memory controller, or evencomponents external to the PAU 400. However, for simplicity, thefollowing examples discuss the processor 305 managing the memory accessbounds checking for atomic operators. Thus, the processor 405 isconfigured to execute an atomic operator with a base memory address ascontext for the execution. In an example, the request to execute the PAOincludes the base memory address. In an example, the request is a CPIrequest, such as the CPI memory request 500. The base memory addresscorresponds to a standard memory address transmitted to a memorycontroller. What varies in this request from standard memory read orwrite requests is the PAO is specified as the operation to be performed.

The processor 405 is configured to obtain (e.g., retrieve or receive) amemory interleave size indicator corresponding to the atomic operator(e.g., from the memory controller interface). In an example, the memoryrequest that invoked the atomic operator includes the memory interleavesize indicator. Again, in systems with multiple memory controllers, thememory interleave size indicates a contiguous portion of memory toallocate to one memory controller before moving on to another memorycontroller for storage. Thus, the interleave operates to stripe acontiguous portion of process virtual memory across several memorycontrollers, and thus often across several memory devices. In somesystems, such as the chiplet system 110, the interleave size isconfigurable, and can be variable from process to process or request torequest.

In an example, the request that invoked the atomic operator is a CPIrequest that includes the memory interleave size indicator, such as theCPI memory request 500 described below. Specifying the memory interleavesize in the request enables greater flexibility to use differentinterleave sizes for different tasks. Further, as described below,because the memory interleave size is used to bound memory requests bythe atomic operator, using an interleave size specified in the requestfor the atomic operator enables developers to tailor the bounds checkingto a specific atomic operator implementation.

The memory interleave size can be represented in a variety of differentformats to balance efficiency of representation (e.g., the number ofbits needed to represent the interleave size) with granularity. In anexample, the memory interleave size indicator is one of four values. Inan example, the four values respectively correspond to two-hundredfifty-six bytes, sixteen kilobytes, one megabyte, and sixty-fourmegabytes. In an example, the four values are integers between zero andthree inclusive. These past few examples are a quantization of thememory interleave size to four predetermined amounts that are encoded bythe integers. Other representations could also be used, including anindex to a lookup. In an example, the memory interleave size indicatoris a bit mask. The bitmask can be useful, as described below, due to thepresence of efficient circuitry to apply the bitmask to achieve aresult. Here, efficiency is not only measured in footprint, but alsotime (e.g., few clock cycles are needed to apply the bitmask to anothervalue).

The processor 405 is configured to calculate a contiguous memory addressrange is calculated from the base memory address and the memoryinterleave size. The calculation can take many forms, such as using thebase address as a center point and then determining a starting addressand ending address by subtracting or adding half of the interleave size.

In an example, the base memory address is at a first end of thecontiguous memory address range. Thus, the base memory address is one oftwo bounds that define the range. In an example, to calculate thecontiguous memory address range from the base memory address and thememory interleave size indicator in the form of a bit mask. Here, therelationship between the base memory address and a memory address in thePAO memory request is close in a continuous memory space, resulting inmany bits of the two memory addresses being the same. The bitmask issized to cover the bits that can potentially be different and stillvalid. Thus, if the base memory address is XORed with the memory addressof the PAO memory request, and the bit mask is applied, the result iszero (e.g., all bits not covered by the bitmask are zeros) when thememory request is in the valid contiguous memory address range. If anyof the bits not covered by the bit mask are not zero (e.g., non-zero),then the memory address of the memory request is not valid because it isoutside the contiguous memory address range. As noted above, using thebitmask to make this calculation can be performed quickly and with lesscircuitry than other techniques.

Calculating the contiguous address range could be performed at any time,such as when the request for the atomic operator was received, justprior to executing the atomic operator, or during execution of theatomic operator. The calculation can even be performed as part of eachmemory request made by the atomic operator while it is executing.

During execution of the atomic operator, the processor 405 is configuredto detect whether a memory request from the atomic operator is outsidethe contiguous memory address range. The detection is straight forward,with the atomic operator being outside of the range if it is lower orhigher than the lower and upper bounds respectively, or inside the rangeif the address of the memory request is between the lower and upperbounds of the range. Whether or not the one bound or the other is withinthe range is an implementation choice.

If the address in a memory request of the atomic operator does not fallwithin the contiguous memory range calculate by the processor 405, theprocessor 405 is configured to deny the memory request. Thus, the atomicoperator bounds checking is accomplished. Because an out-of-boundsmemory request usually entails a problem in the executing atomicoperator kernel, the error can be communicated to the requestor. Thus,in an example, the processor 405 is configured to communicate a failurestatus to an entity that made the request. In an example, the failurestatus is communicated in a CPI response, such as the CPI response 600.Often, such a failed memory request can also suggest that the atomicoperator instructions are more fundamentally flawed. Here, the processor405 can be configured to terminate the atomic operator. Such an actioncould be more efficient by preventing storage, processing capability, orpower from being consumed by the poorly function atomic operator. Insome cases, other benefits, such as preventing data corruption in thememory can also be achieved.

FIG. 5 illustrates a chiplet protocol interface request packet 500,according to an embodiment. The following is a table for an example ofCPI field descriptions and bit lengths corresponding to the CPI requestpacket 500.

Field Field Name Width Value Field Description Line 1 CMD 8 126 Extendedvirtual channel 1 (VC1) LEN 5 Packet Length SC 1 0 Sequence Continue(ignored for external memory device (EMD)) DID 12 Destination NOCendpoint PATH 8 Endpoint Offset <14:7> CP 2 1 Credit/Path Order (CreditReturn enabled in flits 3-N and PATH field based path ordering) Line 2TU 2 Transaction ID <9:8> EPOff <6:0> 7 Endpoint Offset <6:0> TA 8Transaction IS <7:0> EpOffset <33:15> 19 Endpoint Offset <33:15> Line 3EXCMD 8 Extended Command BTYPE 4 8 BTYPE of 8 is EMD vendor defined SID12 Source NOC Endpoint EpOffset <37:34> 4 Endpoint Offset <37:34> RSV 40 Reserved CR/RSV 4 Credit Return Line 4 CrPKnd 4 Credit Pool KindCrPldx 8 Credit Pool Index RSV 4 0 Reserved CaPldx 8 Custom(Programmable) Atomic Partition Index Calntv 8 Interleave Size CR/RSV 4Credit Return Lines 5 and Beyond DATA 32 Argument data: 0, 1, 2, or 4,64-bit values CR/RSV 4 Credit Return

As illustrated, line 4, the shaded line is an extended header 510. Thecommand field 505 indicates that the request 500 is for a PAO. However,the entity decoding the request 500 and providing the PAO parameter to aPAU (e.g., PAU 270) will either pass the extended header 510 informationto the PAU or decode the extended header 510 and provide the constituentfields as inputs to the PAU.

FIG. 6 illustrates a chiplet protocol interface response packet 600,according to an embodiment. The following is a table for an example ofCPI field descriptions and bit lengths corresponding to the CPI responsepacket 600.

Field Field Name Width Field Description Line 1 CMD 8 Packet command LEN5 Encoded packet Length SC 1 Sequence Continue. When set, this packet ispart of a multi-packet transfer and this packet is not the last packetin the sequence. In an example, this bit is present in the first flit ofall packet types. DID 8 Destination NOC Endpoint ID bits <7:0> STAT 4Response Status PATH TID 8 The PATH field used to specify a path througha CPI fabric to force ordering between packets. For both CPI native andAXI over CPI, the read response packet's PATH field can contain atransaction identifier (TID) value. CP 2 Credit Present/Path Ordering.The CP field contains an encoded value that specifies both whether thefield CR of flits 3-N of the packet contains credit return informationand whether path ordering is enabled. Lines 2 and beyond DATA 32 ReadResponse Data, bits N*8-1:0 CR/RSV 4 Credit Return Information RSV 4Reserved

FIG. 7 is a flow chart of an example of a method 700 for memory accessbounds checking for a PAO according to an embodiment. Operations of themethod 700 are performed by computer hardware, such as that describedwith respect to FIG. 1 (e.g., memory controller chiplet), FIG. 2, FIG.3, FIG. 4 (e.g., PAU 400), or FIG. 8 (e.g., processing circuitry).

At operation 705, a PAU (e.g., in a memory controller) executes a PAO.Here, the PAO is being executed with a base memory address. In anexample, a request to execute the PAO is received. In an example, therequest includes the base memory address. In an example, the request isa CPI request, such as the CPI memory request 500.

At operation 710, a memory interleave size indicator corresponding tothe PAO is obtained. In an example, a request to execute the PAOincludes the memory interleave size indicator. In an example, therequest is a CPI request. In an example, the memory interleave sizeindicator is one of four values. In an example, the four valuesrespectively correspond to two-hundred fifty-six bytes, sixteenkilobytes, one megabyte, and sixty-four megabytes. In an example, thefour values are integers between zero and three inclusive. In anexample, the memory interleave size indicator is a bit mask.

At operation 715, a contiguous memory address range is calculated fromthe base memory address and the memory interleave size. In an example,the base memory address is at a first end of the contiguous memoryaddress range. In an example, detecting that the memory request isoutside the contiguous memory address range includes performing anexclusive OR (XOR) operation on the base memory address and a memoryaddress of the memory request to produce a result. Then, the bit mask isapplied to the result to cover lower bits of the result. The uncoveredbits—those bits not masked by the bitmask—of the result are evaluated tofind a non-zero bit. As noted above, finding any bit in the unmaskedresult that is not zero indicates that the memory address is outside ofthe valid contiguous memory address range.

At operation 725, the memory request is denied based on being outside ofthe contiguous memory address range. In an example, where a request wasmade to execute the PAO, denying the memory request includescommunicating a failure status to an entity that made the request. In anexample, the failure status is communicated in a CPI response, such asthe CPI response 600.

FIG. 8 illustrates a block diagram of an example machine 800 with which,in which, or by which any one or more of the techniques (e.g.,methodologies) discussed herein can be implemented. Examples, asdescribed herein, can include, or can operate by, logic or a number ofcomponents, or mechanisms in the machine 800. Circuitry (e.g.,processing circuitry) is a collection of circuits implemented intangible entities of the machine 800 that include hardware (e.g., simplecircuits, gates, logic, etc.). Circuitry membership can be flexible overtime. Circuitries include members that can, alone or in combination,perform specified operations when operating. In an example, hardware ofthe circuitry can be immutably designed to carry out a specificoperation (e.g., hardwired). In an example, the hardware of thecircuitry can include variably connected physical components (e.g.,execution units, transistors, simple circuits, etc.) including a machinereadable medium physically modified (e.g., magnetically, electrically,moveable placement of invariant massed particles, etc.) to encodeinstructions of the specific operation. In connecting the physicalcomponents, the underlying electrical properties of a hardwareconstituent are changed, for example, from an insulator to a conductoror vice versa. The instructions enable embedded hardware (e.g., theexecution units or a loading mechanism) to create members of thecircuitry in hardware via the variable connections to carry out portionsof the specific operation when in operation. Accordingly, in an example,the machine-readable medium elements are part of the circuitry or arecommunicatively coupled to the other components of the circuitry whenthe device is operating. In an example, any of the physical componentscan be used in more than one member of more than one circuitry. Forexample, under operation, execution units can be used in a first circuitof a first circuitry at one point in time and reused by a second circuitin the first circuitry, or by a third circuit in a second circuitry at adifferent time. Additional examples of these components with respect tothe machine 800 follow.

In alternative embodiments, the machine 800 can operate as a standalonedevice or can be connected (e.g., networked) to other machines. In anetworked deployment, the machine 800 can operate in the capacity of aserver machine, a client machine, or both in server-client networkenvironments. In an example, the machine 800 can act as a peer machinein peer-to-peer (P2P) (or other distributed) network environment. Themachine 800 can be a personal computer (PC), a tablet PC, a set-top box(STB), a personal digital assistant (PDA), a mobile telephone, a webappliance, a network router, switch or bridge, or any machine capable ofexecuting instructions (sequential or otherwise) that specify actions tobe taken by that machine. Further, while only a single machine isillustrated, the term “machine” shall also be taken to include anycollection of machines that individually or jointly execute a set (ormultiple sets) of instructions to perform any one or more of themethodologies discussed herein, such as cloud computing, software as aservice (SaaS), other computer cluster configurations.

The machine (e.g., computer system) 800 can include a hardware processor802 (e.g., a central processing unit (CPU), a graphics processing unit(GPU), a hardware processor core, or any combination thereof), a mainmemory 804, a static memory (e.g., memory or storage for firmware,microcode, a basic-input-output (BIOS), unified extensible firmwareinterface (UEFI), etc.) 806, and mass storage 808 (e.g., hard drives,tape drives, flash storage, or other block devices) some or all of whichcan communicate with each other via an interlink (e.g., bus) 830. Themachine 800 can further include a display unit 810, an alphanumericinput device 812 (e.g., a keyboard), and a user interface (UI)navigation device 814 (e.g., a mouse). In an example, the display unit810, input device 812 and UI navigation device 814 can be a touch screendisplay. The machine 800 can additionally include a storage device(e.g., drive unit) 808, a signal generation device 818 (e.g., aspeaker), a network interface device 820, and one or more sensors 816,such as a global positioning system (GPS) sensor, compass,accelerometer, or other sensor. The machine 800 can include an outputcontroller 828, such as a serial (e.g., universal serial bus (USB),parallel, or other wired or wireless (e.g., infrared (IR), near fieldcommunication (NFC), etc.) connection to communicate or control one ormore peripheral devices (e.g., a printer, card reader, etc.).

Registers of the processor 802, the main memory 804, the static memory806, or the mass storage 808 can be, or include, a machine readablemedium 822 on which is stored one or more sets of data structures orinstructions 824 (e.g., software) embodying or utilized by any one ormore of the techniques or functions described herein. The instructions824 can also reside, completely or at least partially, within any ofregisters of the processor 802, the main memory 804, the static memory806, or the mass storage 808 during execution thereof by the machine800. In an example, one or any combination of the hardware processor802, the main memory 804, the static memory 806, or the mass storage 808can constitute the machine readable media 822. While the machinereadable medium 822 is illustrated as a single medium, the term “machinereadable medium” can include a single medium or multiple media (e.g., acentralized or distributed database, or associated caches and servers)configured to store the one or more instructions 824.

The term “machine readable medium” can include any medium that iscapable of storing, encoding, or carrying instructions for execution bythe machine 800 and that cause the machine 800 to perform any one ormore of the techniques of the present disclosure, or that is capable ofstoring, encoding or carrying data structures used by or associated withsuch instructions. Non-limiting machine-readable medium examples caninclude solid-state memories, optical media, magnetic media, and signals(e.g., radio frequency signals, other photon-based signals, soundsignals, etc.). In an example, a non-transitory machine-readable mediumcomprises a machine-readable medium with a plurality of particles havinginvariant (e.g., rest) mass, and thus are compositions of matter.Accordingly, non-transitory machine-readable media are machine readablemedia that do not include transitory propagating signals. Specificexamples of non-transitory machine readable media can include:non-volatile memory, such as semiconductor memory devices (e.g.,electrically programmable read-only memory (EPROM), electricallyerasable programmable read-only memory (EEPROM)) and flash memorydevices; magnetic disks, such as internal hard disks and removabledisks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

In an example, information stored or otherwise provided on the machinereadable medium 822 can be representative of the instructions 824, suchas instructions 824 themselves or a format from which the instructions824 can be derived. This format from which the instructions 824 can bederived can include source code, encoded instructions (e.g., incompressed or encrypted form), packaged instructions (e.g., split intomultiple packages), or the like. The information representative of theinstructions 824 in the machine readable medium 822 can be processed byprocessing circuitry into the instructions to implement any of theoperations discussed herein. For example, deriving the instructions 824from the information (e.g., processing by the processing circuitry) caninclude: compiling (e.g., from source code, object code, etc.),interpreting, loading, organizing (e.g., dynamically or staticallylinking), encoding, decoding, encrypting, unencrypting, packaging,unpackaging, or otherwise manipulating the information into theinstructions 824.

In an example, the derivation of the instructions 824 can includeassembly, compilation, or interpretation of the information (e.g., bythe processing circuitry) to create the instructions 824 from someintermediate or preprocessed format provided by the machine readablemedium 822. The information, when provided in multiple parts, can becombined, unpacked, and modified to create the instructions 824. Forexample, the information can be in multiple compressed source codepackages (or object code, or binary executable code, etc.) on one orseveral remote servers. The source code packages can be encrypted whenin transit over a network and decrypted, uncompressed, assembled (e.g.,linked) if necessary, and compiled or interpreted (e.g., into a library,stand-alone executable etc.) at a local machine, and executed by thelocal machine.

The instructions 824 can be further transmitted or received over acommunications network 826 using a transmission medium via the networkinterface device 820 utilizing any one of a number of transfer protocols(e.g., frame relay, internet protocol (IP), transmission controlprotocol (TCP), user datagram protocol (UDP), hypertext transferprotocol (HTTP), etc.). Example communication networks can include alocal area network (LAN), a wide area network (WAN), a packet datanetwork (e.g., the Internet), mobile telephone networks (e.g., cellularnetworks), plain old telephone (POTS) networks, and wireless datanetworks (e.g., Institute of Electrical and Electronics Engineers (IEEE)802.11 family of standards known as Wi-Fi®, IEEE 802.16 family ofstandards known as WiMax®), IEEE 802.15.4 family of standards,peer-to-peer (P2P) networks, among others. In an example, the networkinterface device 820 can include one or more physical jacks (e.g.,Ethernet, coaxial, or phone jacks) or one or more antennas to connect tothe communications network 826. In an example, the network interfacedevice 820 can include a plurality of antennas to wirelessly communicateusing at least one of single-input multiple-output (SIMO),multiple-input multiple-output (MIMO), or multiple-input single-output(MISO) techniques. The term “transmission medium” shall be taken toinclude any intangible medium that is capable of storing, encoding orcarrying instructions for execution by the machine 800, and includesdigital or analog communications signals or other intangible medium tofacilitate communication of such software. A transmission medium is amachine readable medium. To better illustrate the methods andapparatuses described herein, a non-limiting set of Example embodimentsare set forth below as numerically identified Examples.

Example 1 is an apparatus comprising: an interface configured to obtaina memory interleave size indicator corresponding to a programmableatomic operator, the interface couplable to a memory controller, chipletwithin a chiplet system, or a host device when in operation; aprocessor, coupled to the interface when in operation, configured to:execute a programmable atomic operator, the programmable atomic operatorbeing executed with a base memory address; calculate a contiguous memoryaddress range from the base memory address and the memory interleavesize; detect that a memory request from the programmable atomic operatoris outside the contiguous memory address range; and deny the memoryrequest based on being outside of the contiguous memory address range.

In Example 2, the subject matter of Example 1, wherein the interface isconfigured to receive a request to execute the programmable atomicoperator, the request including the base memory address.

In Example 3, the subject matter of Example 2, wherein the requestincludes the memory interleave size indicator.

In Example 4, the subject matter of Example 3, wherein the memoryinterleave size indicator is one of four values.

In Example 5, the subject matter of Example 4, wherein the four valuesrespectively correspond to two-hundred fifty-six bytes, sixteenkilobytes, one megabyte, and sixty-four megabytes.

In Example 6, the subject matter of any of Examples 4-5 wherein the fourvalues are integers between zero and three inclusive.

In Example 7, the subject matter of any of Examples 2-6, wherein thememory controller is a chiplet in a chiplet PAU, and wherein the requestis in a chiplet interface protocol (CPI) packet.

In Example 8, the subject matter of any of Examples 2-7, wherein denyingthe memory request includes communicating a failure status to an entitythat made the request.

In Example 9, the subject matter of any of Examples 1-8, wherein thememory interleave size indicator is a bit mask.

In Example 10, the subject matter of Example 9, wherein to detect thatthe memory request is outside the contiguous memory address range, theprocessor is configured to: perform an exclusive OR (XOR) operation onthe base memory address and a memory address of the memory request toproduce a result; apply the bit mask to the result to cover lower bitsof the result; and evaluating uncovered bits of the result to find anon-zero bit, the memory request being within the contiguous memoryaddress range when the uncovered bits of the result are all zero, andoutside otherwise.

Example 11 is a method comprising: executing, by a programmable atomicunit (PAU) of a memory controller, a programmable atomic operator, theprogrammable atomic operator being executed with a base memory address;obtaining a memory interleave size indicator corresponding to theprogrammable atomic operator; calculating a contiguous memory addressrange from the base memory address and the memory interleave size;detecting that a memory request from the programmable atomic operator isoutside the contiguous memory address range; and denying the memoryrequest based on being outside of the contiguous memory address range.

In Example 12, the subject matter of Example 11, comprising receiving arequest to execute the programmable atomic operator, the requestincluding the base memory address.

In Example 13, the subject matter of Example 12, wherein the requestincludes the memory interleave size indicator.

In Example 14, the subject matter of Example 13, wherein the memoryinterleave size indicator is one of four values.

In Example 15, the subject matter of Example 14, wherein the four valuesrespectively correspond to two-hundred fifty-six bytes, sixteenkilobytes, one megabyte, and sixty-four megabytes.

In Example 16, the subject matter of any of Examples 14-15 wherein thefour values are integers between zero and three inclusive.

In Example 17, the subject matter of any of Examples 12-16, wherein thememory controller is a chiplet in a chiplet system, and wherein therequest is in a chiplet interface protocol (CPI) packet.

In Example 18, the subject matter of any of Examples 12-17, whereindenying the memory request includes communicating a failure status to anentity that made the request.

In Example 19, the subject matter of any of Examples 11-18, wherein thememory interleave size indicator is a bit mask.

In Example 20, the subject matter of Example 19, wherein detecting thatthe memory request is outside the contiguous memory address rangeincludes: performing an exclusive OR (XOR) operation on the base memoryaddress and a memory address of the memory request to produce a result;and applying the bit mask to the result to cover lower bits of theresult; and evaluating uncovered bits of the result to find a non-zerobit, the memory request being within the contiguous memory address rangewhen the uncovered bits of the result are all zero, and outsideotherwise.

Example 21 is a machine-readable medium including instructions that,when executed by a processor, cause the processor to perform operationscomprising: executing a programmable atomic operator, the programmableatomic operator being executed with a base memory address; obtaining amemory interleave size indicator corresponding to the programmableatomic operator; calculating a contiguous memory address range from thebase memory address and the memory interleave size; detecting that amemory request from the programmable atomic operator is outside thecontiguous memory address range; and denying the memory request based onbeing outside of the contiguous memory address range.

In Example 22, the subject matter of Example 21, wherein the operationscomprise receiving a request to execute the programmable atomicoperator, the request including the base memory address.

In Example 23, the subject matter of Example 22, wherein the requestincludes the memory interleave size indicator.

In Example 24, the subject matter of Example 23, wherein the memoryinterleave size indicator is one of four values.

In Example 25, the subject matter of Example 24, wherein the four valuesrespectively correspond to two-hundred fifty-six bytes, sixteenkilobytes, one megabyte, and sixty-four megabytes.

In Example 26, the subject matter of any of Examples 24-25 wherein thefour values are integers between zero and three inclusive.

In Example 27, the subject matter of any of Examples 22-26, wherein thememory controller is a chiplet in a chiplet system, and wherein therequest is in a chiplet interface protocol (CPI) packet.

In Example 28, the subject matter of any of Examples 22-27, whereindenying the memory request includes communicating a failure status to anentity that made the request.

In Example 29, the subject matter of any of Examples 21-28, wherein thememory interleave size indicator is a bit mask.

In Example 30, the subject matter of Example 29, wherein detecting thatthe memory request is outside the contiguous memory address rangeincludes: performing an exclusive OR (XOR) operation on the base memoryaddress and a memory address of the memory request to produce a result;and applying the bit mask to the result to cover lower bits of theresult; and evaluating uncovered bits of the result to find a non-zerobit, the memory request being within the contiguous memory address rangewhen the uncovered bits of the result are all zero, and outsideotherwise.

Example 31 is a system comprising: means for executing, by aprogrammable atomic unit (PAU) of a memory controller, a programmableatomic operator, the programmable atomic operator being executed with abase memory address; means for obtaining a memory interleave sizeindicator corresponding to the programmable atomic operator; means forcalculating a contiguous memory address range from the base memoryaddress and the memory interleave size; means for detecting that amemory request from the programmable atomic operator is outside thecontiguous memory address range; and means for denying the memoryrequest based on being outside of the contiguous memory address range.

In Example 32, the subject matter of Example 31, comprising means forreceiving a request to execute the programmable atomic operator, therequest including the base memory address.

In Example 33, the subject matter of Example 32, wherein the requestincludes the memory interleave size indicator.

In Example 34, the subject matter of Example 33, wherein the memoryinterleave size indicator is one of four values.

In Example 35, the subject matter of Example 34, wherein the four valuesrespectively correspond to two-hundred fifty-six bytes, sixteenkilobytes, one megabyte, and sixty-four megabytes.

In Example 36, the subject matter of any of Examples 34-35 wherein thefour values are integers between zero and three inclusive.

In Example 37, the subject matter of any of Examples 32-36, wherein thememory controller is a chiplet in a chiplet system, and wherein therequest is in a chiplet interface protocol (CPI) packet.

In Example 38, the subject matter of any of Examples 32-37, whereindenying the memory request includes communicating a failure status to anentity that made the request.

In Example 39, the subject matter of any of Examples 31-38, wherein thememory interleave size indicator is a bit mask.

In Example 40, the subject matter of Example 39, wherein detecting thatthe memory request is outside the contiguous memory address rangeincludes: means for performing an exclusive OR (XOR) operation on thebase memory address and a memory address of the memory request toproduce a result; and means for applying the bit mask to the result tocover lower bits of the result; and evaluating uncovered bits of theresult to find a non-zero bit, the memory request being within thecontiguous memory address range when the uncovered bits of the resultare all zero, and outside otherwise.

Example 41 is at least one machine-readable medium includinginstructions that, when executed by processing circuitry, cause theprocessing circuitry to perform operations to implement of any ofExamples 1-40.

Example 42 is an apparatus comprising means to implement of any ofExamples 1-40.

Example 43 is a system to implement of any of Examples 1-40.

Example 44 is a method to implement of any of Examples 1-40.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples”. Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” can include “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In the appended claims, the terms “including” and“in which” are used as the plain-English equivalents of the respectiveterms “comprising” and “wherein”. Also, in the following claims, theterms “including” and “comprising” are open-ended, that is, a system,device, article, or process that includes elements in addition to thoselisted after such a term in a claim are still deemed to fall within thescope of that claim. Moreover, in the following claims, the terms“first,” “second,” and “third,” etc. are used merely as labels, and arenot intended to impose numerical requirements on their objects.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) can be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features can be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter canlie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment, and it is contemplated that such embodiments can be combinedwith each other in various combinations or permutations. The scope ofthe invention should be determined with reference to the appendedclaims, along with the full scope of equivalents to which such claimsare entitled.

What is claimed is:
 1. An apparatus comprising: an interface configuredto obtain a memory interleave size indicator corresponding to aprogrammable atomic operator, the interface couplable to a memorycontroller, chiplet within a chiplet system, or a host device when inoperation; a processor, coupled to the interface when in operation,configured to: execute a programmable atomic operator, the programmableatomic operator being executed with a base memory address; calculate acontiguous memory address range from the base memory address and thememory interleave size; detect that a memory request from theprogrammable atomic operator is outside the contiguous memory addressrange; and deny the memory request based on being outside of thecontiguous memory address range.
 2. The apparatus of claim 1, whereinthe memory interleave size indicator is a bit mask.
 3. The apparatus ofclaim 2, wherein to detect that the memory request is outside thecontiguous memory address range, the processor is configured to: performan exclusive OR (XOR) operation on the base memory address and a memoryaddress of the memory request to produce a result; apply the bit mask tothe result to cover lower bits of the result; and evaluating uncoveredbits of the result to find a non-zero bit, the memory request beingwithin the contiguous memory address range when the uncovered bits ofthe result are all zero, and outside otherwise.
 4. The apparatus ofclaim 1, wherein the interface is configured to receive a request toexecute the programmable atomic operator, the request including the basememory address.
 5. The apparatus of claim 4, wherein the memorycontroller is a chiplet in a chiplet PAU, and wherein the request is ina chiplet interface protocol (CPI) packet.
 6. The apparatus of claim 4,wherein denying the memory request includes communicating a failurestatus to an entity that made the request.
 7. The apparatus of claim 4,wherein the request includes the memory interleave size indicator. 8.The apparatus of claim 7, wherein the memory interleave size indicatoris one of four values.
 9. A method comprising: executing, by aprogrammable atomic unit (PAU) of a memory controller, a programmableatomic operator, the programmable atomic operator being executed with abase memory address; obtaining a memory interleave size indicatorcorresponding to the programmable atomic operator; calculating acontiguous memory address range from the base memory address and thememory interleave size; detecting that a memory request from theprogrammable atomic operator is outside the contiguous memory addressrange; and denying the memory request based on being outside of thecontiguous memory address range.
 10. The method of claim 9, wherein thememory interleave size indicator is a bit mask.
 11. The method of claim10, wherein detecting that the memory request is outside the contiguousmemory address range includes: performing an exclusive OR (XOR)operation on the base memory address and a memory address of the memoryrequest to produce a result; and applying the bit mask to the result tocover lower bits of the result; and evaluating uncovered bits of theresult to find a non-zero bit, the memory request being within thecontiguous memory address range when the uncovered bits of the resultare all zero, and outside otherwise.
 12. The method of claim 9,comprising receiving a request to execute the programmable atomicoperator, the request including the base memory address.
 13. The methodof claim 12, wherein the memory controller is a chiplet in a chipletsystem, and wherein the request is in a chiplet interface protocol (CPI)packet.
 14. The method of claim 12, wherein denying the memory requestincludes communicating a failure status to an entity that made therequest.
 15. The method of claim 12, wherein the request includes thememory interleave size indicator.
 16. The method of claim 15, whereinthe memory interleave size indicator is one of four values.
 17. Anon-transitory machine-readable medium including instructions that, whenexecuted by a processor, cause the processor to perform operationscomprising: executing a programmable atomic operator, the programmableatomic operator being executed with a base memory address; obtaining amemory interleave size indicator corresponding to the programmableatomic operator; calculating a contiguous memory address range from thebase memory address and the memory interleave size; detecting that amemory request from the programmable atomic operator is outside thecontiguous memory address range; and denying the memory request based onbeing outside of the contiguous memory address range.
 18. Thenon-transitory machine-readable medium of claim 17, wherein the memoryinterleave size indicator is a bit mask.
 19. The non-transitorymachine-readable medium of claim 18, wherein detecting that the memoryrequest is outside the contiguous memory address range includes:performing an exclusive OR (XOR) operation on the base memory addressand a memory address of the memory request to produce a result; andapplying the bit mask to the result to cover lower bits of the result;and evaluating uncovered bits of the result to find a non-zero bit, thememory request being within the contiguous memory address range when theuncovered bits of the result are all zero, and outside otherwise. 20.The non-transitory machine-readable medium of claim 17, wherein theoperations comprise receiving a request to execute the programmableatomic operator, the request including the base memory address.
 21. Thenon-transitory machine-readable medium of claim 20, wherein the memorycontroller is a chiplet in a chiplet system, and wherein the request isin a chiplet interface protocol (CPI) packet.
 22. The non-transitorymachine-readable medium of claim 20, wherein denying the memory requestincludes communicating a failure status to an entity that made therequest.
 23. The non-transitory machine-readable medium of claim 20,wherein the request includes the memory interleave size indicator. 24.The non-transitory machine-readable medium of claim 23, wherein thememory interleave size indicator is one of four values.